1. Field of the Invention
The present invention relates to a method and apparatus for processing biologically hardly degradable waste water including benzene ring materials.
2. Description of the Related Art
Generally, organic waste water is processed by a biological process to remove organic materials from the waste water. In this case, if the organic waste water includes biologically hardly degradable materials such as benzene ring materials, the hardly degradable materials are changed into biologically easily degradable materials before the biological process.
In a first prior art method for processing biologically hardly degradable materials, the materials are oxidized by an oxidizer such as sodium hypochlorite.
In a second prior art method for processing biologically hardly degradable materials (see JP-A-8-192175), the materials are irradiated with ultraviolet rays to produce hydroxyl radical.
In a third prior art method for processing biologically hardly degradable materials (see JP-A-9-103787), the materials with a supporting electrolyte added are electrolyzed by DC.
In a fourth prior art method for processing biologically hardly degradable materials (see JP-A-6-126288), the materials are oxidized by using ozone.
In the above-mentioned prior art methods, the fourth prior art method is most effective for processing a large amount of waste water.
In the fourth prior art method, however, various kinds of oxidation processes may occur simultaneously due to less selectivity of ozone in such oxidation processes, which would consume a large amount of ozone. This will be explained later in detail.
It is an object of the present invention to provide a method and apparatus for processing a biologically hardly degradable waste water including benzene ring materials capable of reducing an amount of consumed ozone.
According to the present invention, in a method for processing a biologically hardly degradable waste water including benzene ring materials, the waste water is oxidized by using ozone to produce oxalic acid. Then, the oxalic acid is reacted using a chemical reaction to produce oxalate. Finally, the oxalate is separated out from the waste water.
Also, in an apparatus for processing a biologically hardly degradable waste water including benzene ring materials, an oxidation cell is provided for oxidizing the waste water using ozone to produce oxalic acid. A chemical reaction cell is connected to the oxidation cell to react the oxalic acid using a chemical reaction to produce oxalate. A separation cell is connected to the chemical reaction cell to separate out the oxalate from the waste water.